Assessment of transformer relay algorithms and settings in laboratory using transient simulation data

This presentation analyses the main operating conditions that may lead to inappropriate differential protection operation. These conditions have been simulated using the Alternative Transients Program (ATP) and a model of a real system. The saturable transformer was the main component of the ATP/EMTP (ElectroMagnetic Transients Program) simulations. The saturation and hysteresis effects are represented by a nonlinear model of the magnetizing inductance. The results of several ATP/EMTP simulations of normal and fault conditions were converted into COMTRADE (COMmon format for TRAnsient Data Exchange for power systems) files. These files were used to verify the performance of relays in low-voltage laboratory tests, using various relay settings.